Your organization requires a process to be initiated via an Appian web API.

The question is about initiating a process via an Appian web API. The HTTP request method that the API should use is POST, as it is the method that allows sending data to the server and creating or updating a resource. In this case, the data would be the process parameters and the resource would be the process instance. The other options are not suitable for this purpose, as they either do not allow sending data or do not create or update a resource. References:

HTTP Request Methods

Start Process Web API